Colorimetric-solid phase extraction method for trace level determination of arsenite in water

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Arsenite [As(III)] is a toxic contaminant in water.
• Accurate and rapid detection methods for As(III) are crucial for environmental monitoring.

Purpose of the Study:

• To develop a sensitive and rapid method for determining inorganic arsenite [As(III)] in water.
• To utilize colorimetric-solid phase extraction (C-SPE) coupled with diffuse reflectance spectrophotometry (DRS) for As(III) analysis.

Main Methods:

• A colorimetric-solid phase extraction (C-SPE) method was developed using a reagent-impregnated SPE membrane.
• The method employs the reaction between arsenite and iodine (I(2)), with excess I(2) complexed by poly(vinyl-pyrrolidone) (PVP) on the membrane.
• Detection of complexed I(2) was performed using a handheld diffuse reflectance spectrophotometer (DRS).

Main Results:

• The C-SPE-DRS method achieved a limit of detection (LOD) below 10 μg L(-1) for As(III).
• The analysis, including sample workup and readout, takes approximately 1-2 minutes.
• The method demonstrated potential effectiveness for analyzing spiked tap water and surface water samples.

Conclusions:

• The developed C-SPE-DRS method offers a rapid, sensitive, and field-deployable approach for inorganic arsenite determination in water.
• The method simplifies analysis by potentially eliminating the need for exact sample volumes under negligible depletion (ND) principles.
• This technique provides a valuable tool for environmental water quality assessment.